From f9aee08dde6b7d7030bbce166f47bb1cf994a8f3 Mon Sep 17 00:00:00 2001
From: Craig Gidney <craig.gidney@gmail.com>
Date: Tue, 13 Aug 2019 12:29:14 -0300
Subject: [PATCH] Work around user-reported error where getProgramInfoLog
 returned null

---
 src/webgl/WglShader.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/webgl/WglShader.js b/src/webgl/WglShader.js
index 4268ef4d..c68ae8eb 100644
--- a/src/webgl/WglShader.js
+++ b/src/webgl/WglShader.js
@@ -150,7 +150,9 @@ class WglCompiledShader {
         gl.attachShader(program, glFragmentShader);
         gl.linkProgram(program);
 
-        let warnings = gl.getProgramInfoLog(program).trim();
+        // Note: MDN says the result of getProgramInfoLog is always a DOMString, but a user reported an
+        // error where it returned null. So now we fallback to the empty string when getting a falsy value.
+        let warnings = (gl.getProgramInfoLog(program) || '').trim();
         if (warnings !== '' &&
                 warnings !== '\0' && // [happened in Ubuntu with NVIDIA GK107GL]
                 Config.SUPPRESSED_GLSL_WARNING_PATTERNS.every(e => !e.test(warnings))) {